1. Field of the Invention
The present invention refers to a method of controlling the transport speed of a transport and gathering path, especially of a gathering path used in a paper handling system.
2. Description of Prior Art
Paper handling systems are primarily used by large enterprises, banks, insurance companies, service-rendering enterprises, etc. In these enterprises, the paper handling systems, which use transport and gathering paths, serve to process large amounts of paper, such as invoices, reminders, statements of account, insurance policies or cheques.
In order to obtain at the end of the paper handling system a suitable compilation of various papers required, it is necessary that the paper handling system correctly processes the different papers when said papers have been printed. The processing takes place at successive stations of the paper handling system and comprises e.g. the steps of separating, folding, sorting, collecting and stapling the various papers as well as subsequent enveloping of the compiled filling material and stamping of the finished letter so that letters ready for dispatch are discharged at the outlet of the paper handling system.
In view of the fact that the above-mentioned different working processes are carried out at successive stations in the paper handling system, it is necessary to provide a connection between these various stations. This connection is established by a so-called gathering path which interconnects the individual stations of the paper handling system.
According to the prior art, the processing speed of the gathering path of such known paper handling systems is fixedly adjusted or it can be adjusted by an operator via operating elements. In apparatus of this kind, the total speed of the gathering path is reduced by the operator for all items processed in the gathering path if the stack height of the filling material is expected to exceed a maximum value. This results in a deterioration of the gathering path throughput.
Such processing systems, especially paper handling systems, are desired to show a broad processing spectrum with regard to the filling-material height and the filling-material weight that can be processed. This broad processing spectrum influences the structural design of the electric drive means. Upon constructing the drive means, two criteria influencing the drive costs and the processing capacity must be taken into account in the known systems.
For a maximum processing capacity, which is referred to as enveloping capacity in paper handling systems, the drive means must firstly be constructed such that, independently of the filling weight and the filling height, they are capable of producing the maximum acceleration moment required for the gathering path of e.g. the paper handling system. In most cases of pratical use, the permitted limit values for which the drive means are constructed are not reached. The structural design of the drive means is therefore oversized and subject to excessively high costs for these cases of use.
If, secondly, the drive means are constructed for a maximum processing capacity with a limited filling-material height and a limited filling-material weight, the system can only be operated at a reduced processing speed in cases of use where higher filling-material heights or higher filling-material weights occur at certain times or constantly. During a production cycle, the limit values admissible for a maximum processing speed are, however, often exceeded only in individual cases. It follows that a processing speed reduced throughout the whole production cycle will only result in an unnecessary reduction of the processing capacity, which is the enveloping capacity in the case of a paper handling system.
DE 3943089 A1 already discloses a means for controlling the operating speed of a processing machine including a feed path which is driven by a drive motor whose operating speed is controlled in dependence upon a distance between products on this feed path, said distance being detected by sensors.